Background Red cell distribution width (RDW) is a novel prognostic marker and independently associated with adverse outcomes in acute decompensated heart failure (ADHF) patients. This study assessed the change in RDW after discharge would have prognostic value in patients with ADHF. Methods and Results RDW was measured in 261 patients admitted with ADHF, at admission and at discharge and one month after discharge. We assessed cardiovascular (CV) events, defined as CV mortality and HF rehospitalization. The Kaplan-Meier analysis showed that patients with positive RDW change between admission and one month after discharge (RDW��1Mdis-adm) (n=136) had significantly higher CV events compared with patients with no-positive RDW��1Mdis-adm (n=125) (60.3% vs. 47.2%, log-rank: p=0.007). In Cox hazards analysis, a positive RDW��1Mdis-adm was an independent predictor of CV events after adjusting other CV risk factors (hazard ratio : 1.740, 95 % CI 1.149-2.633, p=0.009). Conclusions A novel relationship was noted between positive RDW��1Mdis-adm and CV events in ADHF patients. Measurement of RDW at one month after ADHF assists in the prediction of adverse CV outcomes. Therefore, repeated measurement of RDW is a simple and inexpensive method which may help assess the CV risk stratification of patients with ADHF.